Reported illnesses attributed to bathing in natural and artificial waters are described in outlines of three studies conducted by the Public Health Service. Data were gathered as to swimming and illness experience by age, sex, and other groupings. They show that higher illness incidence may be expected in the swimming group than in the non-swimming group regardless of water quality. Eye, ear, and respiratory ailments represent more than half of the overall illness incidence, gastrointestinal up to one-fifth, and skin irritations and other illnesses the balance. It is concluded that some water quality requirements could be relaxed without detrimental effect.