Environmental pollution results in increasing frequency of cyanobacteria blooms occurrence in water reservoirs. Many genera of cyanobacteria may produce toxins which are dangerous for animal and human health. Intoxication may be a result of drinking contaminated water, eating contaminated fish or seafood but also due to skin exposure in recreational water during cyanobacteria bloom. Signs and symptoms of intoxication are unspecific and vary from less serious like skin irritation to death. Accept from confirmation of having contact with contaminated water or food there are no diagnostic tests available. In Poland cyanobacteria blooms occur especially during heat waves. Bellow we present a case of a girl who suffered from an unspecific syndrome after returning from holidays at The Baltic Sea during cyanobacteria bloom occurrence. Few days after swimming in the sea she presented feeling unwell, with fever, skin irritation, visual disturbances, joint pain, slightly elevated inflammatory indicators and proteinuria. On the basis of clinical presentation and results of additional tests we excluded respiratory, gastrointestinal and urinary tract infection. Signs and symptoms disappeared spontaneously within few days of observation. The fact that cyanobacteria bloom occurrence is increasing over the last few years indicates that cyanobacteria intoxication should be taken under consideration while diagnosing unspecific syndrome in children coming back from holidays at the seaside.