This invention relates to piperidine derivatives of formula I wherein R1, R2, R3, R4 and Y are as defined herein useful in the treatment of a variety of disorders, including those in which the modulation of CCR5 receptors is implicated. Disorders that may be treated or prevented by the present derivatives include HIV and genetically related retroviral infections (and the resulting acquired immune deficiency syndrome, AIDS), rheumatoid arthritis, solid organ transplant reject (graft vs. host disease), asthma and COPR.