This review briefly summarizes recent results obtained on the nucleoskeleton of HeLa cells. When the nucleoskeleton is observed in HeLa cells after removal of most chromatin using "physiological" conditions, four structural elements can be recognized: nuclear lamina, core filaments, diffuse skeleton, and nuclear bodies. After dispersing the nucleolar granular component, two additional structures can be visualized: the intranucleolar skeleton, and the fibrillar centers. The relationship between the nucleoskeleton and nuclear synthetic activities-DNA replication and ribosomal transcription-is discussed. The nucleoskeleton is an important nuclear structure, involved in nuclear compartmentalization and probably critical for replication and transcription.