An SPF 30 sunscreen and a proprietary after sun lotion both containing a combination of plankton extract and micrococcus lysate (kindly provided by ATEIA AG, Vaduz, Liechtenstein) was used in a pilot study of intensified photoprotection in patients with multiple skin cancers. Thirteen patients (8 women and 5 men), between 37 and 81 years old, who had had a history of multiple skin cancers were enrolled in the study. Five of the patients had xeroderma pigmentosum (XP) (complementation group: A, 2; C,1; and non-classified 2); one patient XP variant, 3 patients basal cell nevus syndrome, and four patients no skin cancer syndrome. Patients were instructed to apply their sunscreen regularly before sun exposure and 4.5 ml of the after sun lotion to their face and arms daily, as close to mid-day as possible for a period of up to 24 months. The patients were examined in 3-month intervals and the new appearance of actinic keratoses and skin cancers was recorded. New lesions were removed at these visits and the pathology was confirmed by histological examination, except in the cases of (multiple) actinic keratoses, whenever patients agreed. The number of skin tumors during the 24 months of the study was compared to the number in the preceding 24 month-period before study entry. The data were obtained from patient charts and/or electronic files. There was a statistical trend for less BCCs during the study period compared to the prestudy period. In addition, the patients received at each of the 3-month visits a questionnaire and were asked to rate the status of their skin on face and arms during the last 3 months for various parameters on a scale from -2 (maximum worsening) to +2 (maximum improvement). The patients' ratings revealed a statistically significant improvement for several parameters: smoothness, color spots, wrinkles, burning, irritation, teleangiectasia, infections, warts, and skin lesions or sores, starting as early than at the first 3-month visit with a maximum effect seen at 12 months. No adverse effects were noted during the study.