Background Data suggest that photodynamic therapy using topical methyl aminolevulinate (MAL PDT) may be a noninvasive alternative to excisional surgery for nodular basal cell carcinoma (BCC). In the studies described here, we investigated the histologic response, tolerability, and cosmetic outcome with MAL PDT for primary nodular BCC (≤ 5 mm in depth). Methods Two multicenter, randomized, double-blind studies with similar design and procedures were conducted. After surface debridement and minor tumor debulking, MAL cream 160 mg/g (66 patients with 75 lesions) or placebo cream (65 patients with 75 lesions) was applied for 3 h, followed by illumination with broad-spectrum red light (75 J/cm2, 570–670 nm). This was repeated 7 days later. Lesions with a partial response (≥ 50% reduction in greatest diameter) at 3 months were re-treated (21%). Treatment sites were excised at 3 months (clinical nonresponders) or 6 months (clinical responders) after the last treatment. Results Histologically verified lesion complete response rates were higher with MAL PDT than with placebo [73% (55/75) vs. 27% (20/75)]. Treatment was most effective for facial lesions (89% complete response). Cosmetic outcome was good or excellent in 98% of evaluable, completely responding lesions treated with MAL PDT. Conclusion Although longer follow-up studies are required, these promising data indicate the potential of topical MAL PDT as a noninvasive treatment alternative for nodular BCC.