Eicosanoids, which originate from polyunsaturated fatty acids (PUFAs), have a major impact on homeostasis maintenance as secondary signal transducers. Signal cascade, which includes reception, processing and signal transduction coming from the environment into the cell, determines the type of response evoked. Signal distortion may take place on every level of this cascade and this in consequence could lead to the development of many diseases. Any intervention into PUFAs metabolism leads to quantitative and qualitative changes of synthesized eicosanoids. Some of them promote, whereas others inhibit carcinogenesis, some are pro- or anti-inflammatory and the overall result depends on the outcome of these contradictory effects. The type and amount of produced eicosanoids depends on substrates' availability and activity of enzymes catalyzing different stages of their transformation. A particularly negative role was assigned to the over expression of phospholipase A2, cyclooxygenase-2, 5- and 12-lipoxygenases, while the contribution of other oxygenases and their metabolites is considerably less clear. The information about their interplay is extremely sparse and inadequate to understand intricacies of the mechanisms involved. There are indications that utilization of selected eicosanoids (their analogs, agonists or antagonists) could be a better way of disease prevention and treatment, more effective than excessive dietary supplementation of fatty acids. This review presents a more global picture of oxygenases and their PUFA metabolites giving a brief summary of our current understanding of perspectives and pitfalls of their regulation and mediatory action in human diseases.