There are several economically important mite species associated with mango in Puerto Rico. Published reports have associated some of these mites with the mango malformation syndrome (MMS). We give details on a two-year study on the relationship between MMS and mites present in mango nurseries. Common phytophagous mites found in our weekly surveys were the broad mite (Polygophagotarsonemus latus), the mango bud mite (Aceria (=Eriophyes) mangiferae), and Neocalacarus mangiferae, which is a new record for the Caribbean. This mite was described from India in 1966, and reported in Brazil (2000) and Australia (2003). Little is known on the bionomics of this mite. After 26 weeks of observation, we could not associate N. mangiferae with any visible damage to seedlings, as compared to a sprayed control group. This finding may confirm its reported status as a leaf vagrant. Experimental infestations with broad mites (P. latus) showed extensive damage to new leaves, and were an important source of leaf deformation and defoliation, as compared to control seedlings. Mango bud mites caused bud necrosis and loss of seedling apical dominance. We could not clearly associate broad mites with typical MMS symptoms.