diff --git a/internal/check/env.go b/internal/check/env.go
new file mode 100644
index 0000000..932eb9b
--- /dev/null
+++ b/internal/check/env.go
@@ -0,0 +1,83 @@
+package check
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"os"
+	"strings"
+)
+
+type EnvCheck struct {
+	Dir string
+}
+
+func (c *EnvCheck) Name() string {
+	return ".env has all required keys"
+}
+
+func (c *EnvCheck) Run(_ context.Context) Result {
+	exampleKeys, err := parseEnvKeys(c.Dir + "/.env.example")
+	if err != nil {
+		return Result{
+			Name:    c.Name(),
+			Status:  StatusFail,
+			Message: "could not read .env.example",
+		}
+	}
+
+	actualKeys, err := parseEnvKeys(c.Dir + "/.env")
+	if err != nil {
+		return Result{
+			Name:    c.Name(),
+			Status:  StatusFail,
+			Message: ".env file not found",
+			Fix:     "copy .env.example to .env and fill in the values",
+		}
+	}
+
+	var missing []string
+	for key := range exampleKeys {
+		if _, ok := actualKeys[key]; !ok {
+			missing = append(missing, key)
+		}
+	}
+
+	if len(missing) > 0 {
+		return Result{
+			Name:    c.Name(),
+			Status:  StatusFail,
+			Message: fmt.Sprintf("missing keys: %s", strings.Join(missing, ", ")),
+			Fix:     "add the missing keys to your .env file",
+		}
+	}
+
+	return Result{
+		Name:    c.Name(),
+		Status:  StatusPass,
+		Message: fmt.Sprintf("all %d keys present", len(exampleKeys)),
+	}
+}
+
+func parseEnvKeys(path string) (map[string]struct{}, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	keys := make(map[string]struct{})
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+		key, _, _ := strings.Cut(line, "=")
+		key = strings.TrimSpace(key)
+		if key != "" {
+			keys[key] = struct{}{}
+		}
+	}
+	return keys, scanner.Err()
+}
diff --git a/internal/check/env_test.go b/internal/check/env_test.go
new file mode 100644
index 0000000..ef3d2d0
--- /dev/null
+++ b/internal/check/env_test.go
@@ -0,0 +1,54 @@
+package check
+
+import (
+	"context"
+	"os"
+	"testing"
+)
+
+func TestEnvCheck_Pass(t *testing.T) {
+	dir := t.TempDir()
+	os.WriteFile(dir+"/.env.example", []byte("DB_URL=\nAPI_KEY=\n"), 0644)
+	os.WriteFile(dir+"/.env", []byte("DB_URL=postgres://localhost\nAPI_KEY=secret\n"), 0644)
+
+	c := &EnvCheck{Dir: dir}
+	result := c.Run(context.Background())
+	if result.Status != StatusPass {
+		t.Errorf("expected pass, got %v: %s", result.Status, result.Message)
+	}
+}
+
+func TestEnvCheck_MissingKeys(t *testing.T) {
+	dir := t.TempDir()
+	os.WriteFile(dir+"/.env.example", []byte("DB_URL=\nAPI_KEY=\nSECRET=\n"), 0644)
+	os.WriteFile(dir+"/.env", []byte("DB_URL=postgres://localhost\n"), 0644)
+
+	c := &EnvCheck{Dir: dir}
+	result := c.Run(context.Background())
+	if result.Status != StatusFail {
+		t.Errorf("expected fail, got %v", result.Status)
+	}
+}
+
+func TestEnvCheck_MissingEnvFile(t *testing.T) {
+	dir := t.TempDir()
+	os.WriteFile(dir+"/.env.example", []byte("DB_URL=\n"), 0644)
+
+	c := &EnvCheck{Dir: dir}
+	result := c.Run(context.Background())
+	if result.Status != StatusFail {
+		t.Errorf("expected fail, got %v", result.Status)
+	}
+}
+
+func TestEnvCheck_IgnoresComments(t *testing.T) {
+	dir := t.TempDir()
+	os.WriteFile(dir+"/.env.example", []byte("# this is a comment\nDB_URL=\n\nAPI_KEY=\n"), 0644)
+	os.WriteFile(dir+"/.env", []byte("DB_URL=postgres://localhost\nAPI_KEY=secret\n"), 0644)
+
+	c := &EnvCheck{Dir: dir}
+	result := c.Run(context.Background())
+	if result.Status != StatusPass {
+		t.Errorf("expected pass, got %v: %s", result.Status, result.Message)
+	}
+}
diff --git a/internal/check/registry.go b/internal/check/registry.go
index 12e827e..9faa351 100644
--- a/internal/check/registry.go
+++ b/internal/check/registry.go
@@ -35,8 +35,9 @@ func Build(stack detector.DetectedStack) []Check {
 		// add Redis checks
 	}
 
-	// always run env check if .env.example exists
-	// cs = append(cs, &EnvCheck{})
+	if stack.EnvExample {
+		cs = append(cs, &EnvCheck{Dir: "."})
+	}
 
 	return cs
 }
diff --git a/internal/detector/detector.go b/internal/detector/detector.go
index e579a15..3aa2812 100644
--- a/internal/detector/detector.go
+++ b/internal/detector/detector.go
@@ -17,7 +17,8 @@ type DetectedStack struct {
 	Postgres bool
 	Redis    bool
 	MySQL    bool
-	MongoDB  bool
+	MongoDB    bool
+	EnvExample bool
 }
 
 func Detect(dir string) DetectedStack {
@@ -39,6 +40,7 @@ func Detect(dir string) DetectedStack {
 	stack.MySQL = strings.Contains(dbURL, "mysql")
 	stack.MongoDB = os.Getenv("MONGODB_URI") != "" || os.Getenv("MONGO_URL") != ""
 	stack.Redis = os.Getenv("REDIS_URL") != "" || os.Getenv("REDIS_URI") != ""
+	stack.EnvExample = fileExists(filepath.Join(dir, ".env.example"))
 
 	return stack
 }